pgAdmin v1.8.4, Windows XP SP3 Okay, this is a very picky little bug. There is a line of maybe 2 pixels underneath the DB connection dropdown box on the Query screen, and also under the row limit dropdown on the Edit data screen that fails to draw correctly.
It is transparent, so if you have the main pgAdmin window underneath it it looks grey like it should. If you have something else under it, such as your desktop or another window, you see that there instead. This doesn't affect usability or stability or anything else, but it bugs me so I figured I'd bring it to someone's attention. Thanks for your time, Rob.